The present invention relates generally to eyewear, especially liquid crystal eyewear, whose light transmissivity can be varied and more particularly to eyewear whose transmissivity can be varied in response to and as a function of directionally controlled ambient light and still more particularly to eyewear of this type in which its light transmissity can also be varied in response to and as a function of the light intensity of a cooperating head mounted display, a computer display or other such display which is used outdoors.
Liquid Crystal eyewear used as light variable sunglasses are known in the art. For example, see for example U.S. Pat. No. 5,952,988 that issued to Moddel and that is incorporated herein by reference. This particular design and others in the art use a photo-detector to measure the ambient light reaching the glasses and changes in light transmissivity depending on the ambient light level. A problem with these different eyewear designs is that they respond generally to the surrounding ambient light. Thus, if it is a sunny day but the user, who is standing in the sun, is looking into the shade, the surrounding light will cause the eyewear to darken making it more difficult to see into the shade. As will be seen hereinafter, the present invention solves this problem by making the eyewear respond directionally to the ambient light and, thus, provides an advantage to the user who wished to focus his or her attention in a specific direction.
Another advantage of the present invention, as will also be seen, is its use with head mounted displays and computers intended to be used in ambient light of varying intensity, for example outdoors. The eyewear is designed in accordance with the present invention such that its light transmissivity is, at least in part, made responsive to and a function of the general light level of the display. Thus, in the case of, for example, a head mounted display in which the user views the display with one eye outdoors, the other eye which would otherwise be subject to the variability of ambient outdoor light can be protected by the eyewear. That is, the eyewear in accordance with the present invention can be controlled in cooperation with the head mounted display so that the light intensity reaching both eyes of the user are approximately the same.
As will be disclosed in more detail herein after, the present invention, in accordance with one embodiment provides for a light modulating cell assembly especially suitable as eyewear, comprising: (a) a light modulating cell arrangement including a light modulating medium, preferably liquid crystal, positionable in front of the eye of a user and configured so as to be able to change the state of its light modulating medium in a way which changes the transmissivity of light passing through the light modulating medium from the ambient surroundings before reaching the eye; (b) a light transmissivity control arrangement including a light detector for changing the light modulating state of said light modulating medium, at least in part, in response to and as a function of the level of light reaching said detector from the ambient surroundings; and (c) a light blocking arrangement at least partially surrounding said detector for allowing only light from a limited range of ambient directions to directly reaching said detector.
In accordance with another embodiment there is provided a light modulating cell assembly especially suitable for use for eyewear and for use with a head mounted display or a computer display having its own light intensity, comprising: (a) a light modulating cell arrangement including a light modulating medium, again preferably liquid crystal, positionable in front of the eye of a user and configured so as to be able to change the state of its light modulating medium in a way which changes the transmissivity of light passing through the light modulating medium from the ambient surroundings before reaching the eye; and (b) a light transmissivity control arrangement including auxiliary means for controlling the state of said light modulating medium such that the light passing through the light modulating medium from the ambient surroundings is maintained at a controlled intensity, at least in part, in response to and as a function of the light intensity of said display and so long as the ambient light which would otherwise reach said light detector does not drop below that intensity.